This invention relates to a gear pump and, more particularly, to a gear pump which is especially designed to supply pressurized liquid fuel to an oil burner. Gear pumps of this general type are disclosed in Harwath U.S. Pat. No. 4,171,939; Hunsberger et al U.S. Pat. No. 4,395,580 and Harwath U.S. Pat. No. 4,685,871.
In a gear pump, it is conventional for a spur gear to be secured by a key to the free end portion of a rotatable drive shaft. The key fits into radially opening slots or keyways in the gear and the shaft and couples the gear and the shaft for rotation in unison. The keyway in the shaft opens axially out of the free end of the shaft to enable the shaft to be assembled with the gear and the key by telescoping the shaft axially into a hole in the gear.
Most conventional gear pumps with a key/slot drive of the type described above are equipped with a so-called face seal for establishing a liquid-tight seal between the shaft and the body of the pump. By its very nature, a face seal prevents relative axial movement between the shaft and the pump body and thus the face seal serves to hold the shaft and the gear in axially assembled relation.
Other gear pumps are provided with a so-called lip seal between the shaft and the pump body. Depending on the pressure, temperature or other characteristics of the particular liquid being pumped, lip seals are sometimes preferred over face seals. A lip seal, however, is not capable of preventing axial movement of the shaft and thus some other means must be used to hold the shaft and the gear in axially assembled relation.